The invention relates to the elimination of organic pollutants from the air of a motor-vehicle passenger compartment, this vehicle being equipped with a heating, ventilation and/or air-conditioning installation arranged under the dashboard.
Toxic- or polluting-gas-filtration apparatus for a vehicle passenger compartment is known from EP 0 798 143, this apparatus using photocatalysis as active principle. The photocatalyst is deposited in powder form on a fibrous medium. The ultra-violet source consists of a lamp situated in proximity to the medium so as to obtain optimal irradiation. This apparatus is self-contained and is placed preferably on the rear shelf of the vehicle. The air to be treated is put into motion by a blower incorporated in the apparatus and passes through the irradiated medium. The cleaned air is sent back into the passenger compartment. During the periods of reactivation of the photocatalyst, the polluted gases are directed towards the air filter of the engine so as to be burned in the engine. This apparatus thus requires a duct to be installed for sending the polluted gases to the engine.
Wo 96/37 280 also envisages the use of a layer of photocatalyst irradiated by natural or artificial UV in order to eliminate organic pollutants from the passenger compartment of the vehicle. In the case of the use of natural UV, this document makes provision for the inner face of the windshield to be covered with a thin layer of photocatalyst. This document also suggests covering elements of the ventilation system, especially the vanes of the blower, with a layer of photocatalyst, which are then irradiated by a lamp emitting in the ultra-violet range.
The use of the windshields as a support for the photocatalyst layer makes it necessary to deposit a layer of photocatalyst which is fine and uniform enough not to distort the vision of the driver of the vehicle. This entails an intricate and expensive manufacturing process.
The object of the invention is to propose a method of eliminating pollutants from a vehicle passenger compartment which is easy to implement and inexpensive.
According to the present invention there is provided a method of purifying the air of the passenger compartment of a vehicle equipped with a heating, ventilation and/or air-conditioning installation arranged under the dashboard, the method comprising:
providing a photocatalyst deposited on a support; and
irradiating the said photocatalyst by light rays, wherein at least a part of the interior fittings of the passenger compartment serves as support for the photocatalyst.
Advantageously the dashboard is used as support for the photocatalyst.
Advantageously at least the outer face of the dashboard, which is visible from the passenger compartment, is covered by a layer of photocatalyst, this layer being irradiated at least by natural visible or ultra-violet rays.
According to another characteristic of the invention, an installation is provided capable of delivering a throughput of ventilation air through a diffusion chamber arranged under the dashboard and communicating with the passenger compartment via a plurality of orifices formed in the wall of the dashboard.
Thus the ventilation air exits at low speed from the dashboard, and laps its outer surface which is covered with a photocatalyst and irradiated by the ultra-violet or natural visible passing through the windshield.
According to another advantageous characteristic of the invention, the inner face of the dashboard, which is situated in the diffusion chamber, is covered with a layer of photocatalyst which is irradiated with a source of ultra-violet rays arranged in the said diffusion chamber, and means are provided for masking the orifices of the wall of the dashboard from the emission of the ultra-violet from the source.
According to a first embodiment, the masking means include a supplementary wall forming a chicane in the diffusion chamber, and covered with a layer of photocatalyst irradiated by the ultra-violet from the source.
This wall may include apertures which are offset with respect to the orifices of the dashboard.
According to a second embodiment, the dashboard includes a plurality of fixed vanes covered on both of their faces by a layer of photocatalyst and oriented in such a way as to mask the air outlets from the emission of the ultra-violet rays from the source.